More improvements to CircleCI configuration (#2777)

* Moved configuration to `.circleci/config.yml` as the documentation for V2 suggests.
* Created a dedicated Docker Compose configuration (in `.circleci/docker-compose.yml`) to remove volumes configuration as this is not supported with CircleCI's Docker executer.
* Fix the Docker image build and tarball packing jobs to work and use correct version.

bin/get_changes.py

@@ -0,0 +1,35 @@
+#!/bin/env python
+import sys
+import re
+import subprocess
+
+def get_change_log(previous_sha):
+    args = ['git', '--no-pager', 'log', '--merges', '--grep', 'Merge pull request', '--pretty=format:"%h|%s|%b|%p"', 'master...{}'.format(previous_sha)]
+    log = subprocess.check_output(args)
+    changes = []
+
+    for line in log.split('\n'):
+        try:
+            sha, subject, body, parents = line[1:-1].split('|')
+        except ValueError:
+            continue
+
+        try:
+            pull_request = re.match("Merge pull request #(\d+)", subject).groups()[0]
+            pull_request = " #{}".format(pull_request)
+        except Exception as ex:
+            pull_request = ""
+
+        author = subprocess.check_output(['git', 'log', '-1', '--pretty=format:"%an"', parents.split(' ')[-1]])[1:-1]
+
+        changes.append("{}{}: {} ({})".format(sha, pull_request, body.strip(), author))
+
+    return changes
+
+
+if __name__ == '__main__':
+    previous_sha = sys.argv[1]
+    changes = get_change_log(previous_sha)
+
+    for change in changes:
+        print change